1. Field of Invention
The present invention relates to modular refractory fiber blanket furnace lining systems.
2. Description of Prior Art
Refractory fiber blankets made from refractory materials such as chromia-alumina-silica, alumina-silica compositions and zirconia compositions have become desirable as furnace insulation because of their ability to withstand high temperatures. The fiber blanket material has been attached in a layered construction arrangement to the furnace wall using attachment structure, as exemplified in U.S. Pat. Nos. 3,523,395 and 3,605,370. Another technique is to fabricate the refractory fiber blankets into modules, as in U.S. Pat. Nos. 3,819,468 and 3,832,815.
With these refractory fiber blanket modules, heat shrinkage of the ceramic fibers during service along those faces of the modules closest to interior conditions in the furnace, known as the "hot face," could cause cracks or fissures and form paths for undesirable heat flow from the interior of the furnace torwards the wall of the furnace.
One approach has been to arrange the modules in a parquet-like construction, as shown in these U.S. Pat. Nos. 3,819,468 and 3,832,815. In U.S. Pat. No. 3,832,815, the individual modules were formed from trapezoidal configuration individual blanket strips which were thicker at the hot face than adjacent the surface to be mounted with the furnace wall. This configuration was intended to exert compressional forces between adjacent modules once installed in the parquet-like configuration and compensate for shrinkage of the fibers. However, cutting blanket strips to this trapezoidal configuration caused difficulties.
Additionally, in both U.S. Pat. No. 3,819,468 and 3,832,815 the blanket strips were attached by being speared at one end, near the cold face thereof, and suspended therefrom. Often during service use, the suspended blanket might slip or come loose due to being mounted in this manner. Further, so far as is known, when so installed, the general orientation of fibers in the blankets was in the direction of heat flow from the hot face to the cold face. This type of fiber orientation did not permit use of optimum insulation characteristics of the blanket, which occurs when the fibers are generally oriented transversely to the direction of heat flow.